Portable tunnel kiln



Jan. 10, 1956 Filed Dec. 29, 1950 wig I X Illlllllll F. W. PETERSONPORTABLE TUNNEL KILN 3 Sheets-Sheet 1 INVENTOR. Forrest W. Peterson,

ATTORNEY Jan. 10, 1956 F. w. PETERSON PORTABLE TUNNEL KILN 5Sheets-Sheet 2 Filed Dec. 29, 1950 INVENTOR. Forrest W. Peterson,

ATTORNEY Jan. 10, 1956 F. w. PETERSON PORTABLE TUNNEL KILN Filed Dec.29, 1950 3 Sheets-Sheet 3 INVENTOR. Forrest W. Peterson, BY

ATTORNEY United States Patent 2,729,872 PORTABLE TUNNEL KlLN Forrest W.Peterson, Burbank, Califi, assignor, by nresne assignments, to FerroCorporation, Cleveland, Ohio, a corporation of Ohio This inventionrelates generally to kilns and relates more particularly to tunnelkilns.

Tunnel kilns heretofore have generally been permanently installed andthe plant laid out around the immovable kiln. Once installed the kilncould not be moved about and any attempt to move it would result inserious damage thereto.

It is therefore an object of the present invention to provide a tunnelkiln which will overcome the above disadvantageous features.

It is another object of the invention to provide apparatus of thischaracter which is readily portable.

It is still anotherobject of the invention to provide a device of thischaracter that may be easily installed in a relatively short time.

It is a further object of the invention, to provide apparatus of thischaracter incorporating flexible structural features so that it will notbe damaged when moved with reasonable care. i I

It is a still further object of the invention to provide apparatus ofthis character having high efliciency and improved temperature control.i

It is another object of the invention to provide apparatus of thischaracter that will occupy a relatively small space. i i i It is stillanother object of the invention to provide apparatus of this characterwhichmay be produced at relatively low cost.

Further objects and advantages of the invention will appear in thefollowing part of the specifications.

Referring more particularly to the drawings which are for illustrativepurposes only;

Fig. l is an isometric view of a kiln embodying the present invention;

Fig. 2 is an enlarged sectional view taken of Fig. 1;

Fig. 3 is a sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a sectional view taken on line 4--4 of Fig. 2;

on line 2--2 Fig. 5 is an enlarged fragmentary isometric view of a 1joint of the muffle;

Fig. 6 is an enlarged fragmentary view taken on line 6-6 of Fig. 2; and

Fig. 7 is an enlarged view of one ofthe screwsfor vertically adjustingthe end tunnel sections.

Referring more particularly to Fig. 1, the kiln includes an entrancesection, indicated generally at 10, an intermediate section, indicatedgenerally at 11,and an outlet section, indicated generally at 12., p

The entrance section includesa tunnel portion 13 having side walls 14constructed of suitable masonry, such as refractory brick, a bottom 15of refractory tile and a top 16 which is also formed of refractory tile.Adjacent the inner bottom corners are longitudinally extend- 2,729,872Patented Jan. 10, 1956 2 ing guides 17 which are also formed of suitablerefractory material.

The entrance tunnel is supported on a metal framework, indicatedgenerally at 18, comprising upper and lower longitudinal side sections19 and 20 respectively inter connected by support members 21 and upperand lower cross members 22 and 23. A pair of rails 24 are mounted on theframe 18 in parallel relationship and in alignment with the guides 17,said rails being for supporting slabs which are moved by suitable pushermechanism not shown but which is of known character. The frame 18 isvertically adjustable by means of adjusting screws 26, there being onesuch screw at least at each corner of the frame. Vertical adjustment ofthe entrance tunnel section is effected by said screws 26 to positionthe inner end thereof in line with the recess 74 prior to insertion ofsaid inner end in said recess.

The tunnel portion of the intermediate section 11 of the apparatuscomprises side walls 30 of refractory brick and/or insulation, suchconstruction being well known. The tunnel also has a bottom wall 31 anda top wall 32 suitably formed of refractory tile and/or insulatingmaterial or the like. The outer sides of the walls 30 are covered bysheets 30a of insulating material and the top 32 is covered with agranular insulating material 320, both the sheets 30a and material 32abeing Well known.

The masonry of the tunnel portion is supported in a frame-work of steel,indicated generally at 33, which, as shown, comprises plates 34 on whichthe bottom 31 of the tunnel rests, said plates 34 being reinforced byangleirons 35. Beneath the plates 34 are channel members 36 and 37, themembers 36 running longitudinally of the tunnel and the members 37extending transversely between the members 36 for connecting the endsthereof together. I beams 38 form the bottom supports for the frame andextend longitudinally thereof, the I beams 38 being connected to thechannels 36 by vertical channel members 39. The tunnel portion isreinforced by steel members 40 along the various edges thereof. Metalside members 40:: connect the frame-work 33 with the frame members 40.

Within the tunnel of the intermediate section are arranged a pluralityof pilasters 45 which are spaced apart longitudinally of the tunnel andalso transversely of said tunnel, said pilasters extending upwardly fromthe bottom 31 and being formed of refractory brick.

The pilasters 45 provide supporting means for the muflle which isconstructed of refractory material and which includes a bottom formed oftile 46. A second layer of tile 47 is provided on the tile 46, saidsecond layer could, of course, be of brick. Guides 48 also rest on thetile 46 and extend alongside of the tile 47, the guides 48 being ofrefractory material and being spaced inwardly from the side edges of thetile 46. The masonry parts thus far described are secured together withmortar.

The side walls of the muifie comprise tile slabs 50 of refractorymaterial and said slabs: are secured in position by having their endsloosely received in grooves 51 of mufiie holding bricks 52. The mufiieholding bricks are arranged to form vertical partitions, said brickshaving their outer sides in engagement with the inner side of the tunnelwalls 30. As shown, the bricks 52 are arranged in end-wise engagementwith each other and the grooves 51 are formed in the sides for loosereception of the adjacent ends of the tile members 50. It will be notedthat the lower of the bricks 52 have portions 52a which extend over thebottom tile members 46 and rest thereon, the lower tiles being notchedat 55 to accommodate the adjacent guides 48. The upper holder bricks52have notches 52b at their inner upper ends forreception of adjacentside edge portions of the tile members 56 which form the top of themuffle. It is to be noted that the mufile holder bricks 52', the sidetile members 50 and the top tile members 56 are loosely assembled andsecured together without mortar, the joints being dry slip joints havingsome play, about 2/8. It is also to be noted that the side tile members50 r'est on the bottom tile members 46 and are not secured thereto bymortar. Thus the muflle will stand considerable twisting or distortionwithout breaking at the jointsor cracking of the parts.

It will be noted that the top, bottom and side walls of the muffle arein spaced relation to the respective parts of the tunnel, to permit thepassage or circulation of heated air about said mufile. Also the muffieholder bricks 52 are arranged to form vertical partitions between theside walls of the muffle and the adjacent side walls of the tunnel, saidpartitions preventing the drifting of hot air longitudinally of thetunnel.

Thebottom 31 of the tunnel isprovided with a plurality of openings 60therein which are spaced longitudinally apart from the entrance end ofthe intermediate section. Disposed in said openings 60 are heatingdevices shown as gas burners 61 which are supplied with gas through asupply pipe 62 connected with any suitable source of fuel supply.

Further along in the intermediate section are a plurality of openings 63some of which are arranged in pairs, as best shown in Fig. 3 and whichhave gas burners 64 disposed therein and connected to the supply pipe62. Peep holes 67 are provided in one of the side walls of the tunnel.

Further on is a portion of the tunnel which is provided with a pluralityof openings 68 in the bottom 31 for cold air, as will be hereinaftermore fully described. Above the mufile is a chamber 70 which extendslongitudinally of the intermediate section and which has a plurality ofoutlets 71 therein disposed generally in the portion of the apparatuscontaining the openings 63. Means may be provided for controlling theefiective size of the openings 71, such means may be, for example,damper bricks 75a which may be provided for any or all of said openings71. The portion of the intermediate sectionincluding the longitudinallyspaced openings 68 a is closed ofi from the rest of the section by apartition 72 and said portion has a plurality of outlet openings 73 inthe upper wall 32 of the tunnel.

The entrance end of the intermediate section is provided with a recess74 for the reception of an adjacent end portion of the entrance tunnel13, as best shown in Fig. 2, and the opposite end of the intermediatesection is provided with a similar recess 75 for reception of theadjacent end portion of the outlet tunnel, indicated genorally at 76.

The outlet section of the tunnel comprises side walls 77 of refractorybrick, a bottom of refractory tile 79 and a top of refractory tile 80.The construction of the outlet .tunnel section is similar to theconstruction of the inlet tunnel section but the outlet section islonger than said inlet section. The outlet section 76 is supported on ametal framework, indicated generally at 85, and includes parallel upperand lower members 86 and 87 on each side, said members 86 and 87 beingvertically spaced apart and connected together by suitable beams or thelike 88 and connected together to the corresponding members on theopposite side with transverse members 89. The framework 85 extendsbeyond the free end of the outlet section and is provided with rollers90 as best shown in Fig. 1.

the recess 75 so that said inner end may be inserted in saidrecessl Inoperation, the ware to be fired, such as the articles in Fig. 2, is puton slabs 96 at the entrance where the pusher mechanism, not shown, canmove the slab along the rails 24. As each slab is pushed into thetunnel, the previously inserted slabs are pushed along.

The initial portion of the entire course traversed by the ware isconsidered the pre-heat zone and extends from the opening of theentrance section 13 to the adjacent end of the intermediate portion ofsection 11 which includes an intermediate part of the Inuffle having thetop wall raised as indicated generally in 97 in Fig. 2. In other words,the pre-heat zone extends from the entrance of the kiln to the point 98,Fig. 2, and from this point to the partition 72 there is what is termedthe hot zone where the ware is subjected to an intense firing. Beyondthe hot zone to the end of the intermediate section is the controlledcooling zone and further cooling occurs in the outlet section '12. Theslabs carrying the ware through the apparatus are pushed onto therollers when they leave the outlet section 76 and the ware is thenunloaded from the slabs, which are then removed from the rollers. V

The air heated by the burners 61 surrounds the muffle in the pre-heatzone and passes from the lower portion of the tunnel, about the sides ofthe muffle, into the chamber 70, and thence is discharged through theoutlet openings 71 in the top 32 of the tunnel. As hereinbefore pointedout, the partitions formed by the muffle holders between the sides ofthe mane and the adjacent sides of the tunnel prevent the hot air fromdrifting longitudinally in the tunnel. I

The heated air in the hotzone follows a similar course and is, likewise,prevented from drifting in the tunnel by the partitions formed by themuffle holder bricks.

Whenthe air passes through the controlled cooling portion of theintermediate section, cold air passes upwardly into the openings 68,about the muffle portion, extending through the controlled cooling zoneof the apparatus, and out through the outlet'openings 73. Here again,the partitions formed by the muffle holding bricks prevent drifting ofthe cool air and it is to be noted that said cool air may pass throughthe apparatus with or without forced draft. The muffie is also providedwith a sulphur vent 56a.

It has'been found'that there is a considerable reduction in the drift ofheated air within the muffle due to the portions 100 of the muffleholder bricks which extend into the interior of the muffle at the sidesthereof and act as baffles within said, muffle. It will, therefore, beobvious from the foregoing that the present apparatus provides greatlyimproved temperature control so that there is a more uniform temperatureapplied to the ware being fired and hence there are improved resultsderived from the firing. It has also been found that by using thecontrolled cooling of the present invention and the subsequent coolingin the outlet section that the ware can be handled with the bare handsassoon as it is discharged from the tunnel. .This is an extremelyadvantageous feature. ,Moreover, because of the high efiiciency ofthepresent invention, the apparatus is relatively small in size.

By building the present kiln in a plurality of sections, it is possibleto transport said sections. The lower portions of the frame, such as themembers 20, 38 and 87 of the respective entrance, intermediate andoutlet sections, serve as skids and rollers may be used beneath saidskids to facilitate moving the sections whether on the ground orfoundation or onto and oif of trucks for transporting same. Due to thefact that the muflie'is flexibly assembled, such twisting or distortionas may occur in moving the various sections will not cause the muffle tobreak or crack.

When the apparatus is being assembled, the entrance and outlet sectionsmay be raised or lowered and leveled by means of the jack screws 26 sothat said sections are brought into alignment with the various parts ofthe intermediate section. :Also, a hood may be disposed over theopenings 71 to provide means for carrying 011 the heated air dischargedfrom said openings 71.

It is to be understood that the tunnel sections may be constructed ofother material than refractory brick and/ or tile. There are variousknown insulating materials which may also be used instead of or inconjunction with said brick and/ or tile.

I claim:

1. A pusher slab type tunnel kiln, comprising: a plurality of tunnelsections removably connected together; skids for supporting eachsection; means for adjusting at least one section vertically relative toanother section; and a muffle extending longitudinally in at least onesection, said mufiie being formed of refractory material and having dry,slip joints so that said mufile is relatively flexible.

2. A portable pusher slab type tunnel kiln, comprising: a plurality oftunnel sections removably connected together; skids for supporting eachsection; and a mufile extending longitudinally in at least one section,said muffle being formed of refractory material and having dry, slipjoints so that said muflie is relatively flexible.

3. A portable pusher slab type tunnel kiln, comprising: a plurality oftunnel sections removably connected together; skids for supporting eachsection; and a muffle extending longitudinally in at least one section,said mufile being formed of refractory material and having dry, slipjoints so that said muffle is relatively flexible, said kiln having apre-heat zone, a hot zone and a controlled cooling zone.

4. A pusher slab type tunnel kiln, comprising: a plurality of tunnelsections removably connected together; skids for supporting eachsection; and a muifie extending longitudinally in at least one section,said muflle being formed of refractory material including slab-likemembers and holding bricks provided with grooves in which portions ofsaid slab-like members are loosely received, said holding bricks beingarranged to form vertically extending partitions between the muflle andthe adjacent walls of the tunnel; and a partition wall between themuffle and tunnel walls, said partition wall being spaced from thedischarge end of the tunnel section.

5. In a kiln: a tunnel section having a bottom wall, side walls and atop wall, the bottom wall having a plurality of openings spacedlongitudinally apart, and the top wall being provided with a pluralityof openings spaced from each other; a muffle extending longitudinallywithin the tunnel section; means for supporting the rnufile in spacedrelation to the bottom wall of the tunnel, said means comprising aplurality of supports spaced from each other; and a partition wallbetween the muffle and the respective side walls of the tunnel, saidpartition wall being spaced from the discharge end of the tunnelsection, some of the openings in the bottom wall and top wall beingbetween the partition wall and the outlet end of the tunnel section.

6. In a kiln: a plurality of tunnel units, each unit having a structureof refractory material forming a tunnel; metal frame-work for each unitfor supporting the re fractory structure, one of said units having arecess in one end for reception of the adjacent end of the other unit sothat the tunnels thereof are in register for forming a tunnel throughthe kiln; and means for at least one of the units for leveling same soas to bring the tunnel of said other section into register with thetunnel of said one section whereby the sections may be joined.

References Cited in the file of this patent UNITED STATES PATENTS1,178,184 Simpson Apr. 4, 1916 1,285,862 Wiester Nov. 26, 1918 1,295,564Morton Feb. 25, 1919 1,361,604 Milner et al Dec. 7, 1920 1,389,583Frazier Sept. 6, 1921 1,471,875 Witte Oct. 23, 1923 1,472,139 Reid Oct.30, 1923 1,520,408 Ebeling Dec. 23, 1924 1,548,794 Fuller Aug. 4, 19251,613,054 Prouty et a1. Jan. 4, 1927 1,661,309 Saxe Mar. 6, 19281,827,543 Robertson Oct. 13, 1931 1,903,281 Bowman Apr. 4, 19332,399,664 Clark May 7, 1946

